How can we comfort our 17-month-old, who wakes up terrified and won't go back to sleep?
This behavior is not unusual for a child who is going through a period of separation anxiety. Sometimes this begins after your child has awakened to a babysitter or grandparent that they did not know or forgot was going to be there instead of a parent. Periods of separation anxiety coincide with periods of increased mobility and developmental leaps. Because of nighttime fears generated by this new freedom, children need to seek out a loved one that is out of sight to make sure he or she hasn't disappeared.
You are right to respond to this need but you can help him learn to sleep alone again by gradually doing less and less over a period of two to three weeks. Let him have an object such as a stuffed animal or a soft "blankie" to hold while you comfort him and sleep with him in his room. Then, each night, move slightly farther from his side until he settles with a minimum of fuss, perhaps with you merely in the room. Soon he will need only reassurance and his "blankie" to go back to sleep.